Field of the Invention
The present invention relates to an imaging device including an optical waveguide provided above a photoelectric converter.
Description of the Related Art
In recent years, a video camera, an electronic still camera, and other such imaging system have become generally widespread. A CCD, a CMOS image sensor, and other such imaging device are used for those cameras. As a technology for improving sensitivity of those imaging devices, it is proposed to provide an optical waveguide above a light-receiving surface of a photoelectric converter of each pixel. In Japanese Patent Application Laid-Open No. 2009-164247, there is disclosed a solid-state imaging device including optical waveguides arranged above photoelectric conversion elements.
The imaging device includes an effective pixel region in which pixels for outputting a signal of an image are arranged, and also includes an optical black (OB) region in which pixels for outputting a reference signal to be used as a reference for a black level are arranged. In order to acquire a better-quality image, it is important to reduce a difference in output of a dark signal between the pixels arranged in the effective pixel region and the pixels arranged in the OB region.